The colossal S2 meteorite triggered environmental changes that may have promoted early bacterial life on Earth.

A massive meteorite, dubbed the S2, struck Earth around three billion years ago, triggering the largest tsunami in the planet’s history and potentially creating conditions that helped life to flourish. Measuring between 37 and 58 kilometres in diameter (approximately the size of Mount Everest), S2 hit a young Earth and caused monumental environmental upheavals, with both destructive and life-boosting consequences.

According to new research published in the Proceedings of the National Academy of Sciences, the impact was catastrophic on an immediate scale, but over time it may have paved the way for life to thrive. Nadja Drabon, an early-Earth geologist and assistant professor at Harvard University, said the study challenges the usual perception of meteorite impacts as solely disastrous. “What this study is highlighting is that these impacts would have had benefits to life, especially early on,” she said.

The S2 meteorite dwarfed the impact that wiped out the dinosaurs 65 million years ago, being approximately 200 times larger. Upon striking Earth, it unleashed a colossal tsunami that mixed the world’s oceans, sweeping vast amounts of land debris into coastal waters. The heat generated by the impact boiled away large portions of the oceans’ upper layers and heated the atmosphere, while a thick blanket of dust blocked sunlight, reminiscent of the conditions following the dinosaur extinction event.

Despite the immediate destruction, life quickly rebounded. In particular, iron-metabolising bacteria seem to have proliferated after the event. Drabon’s research points to iron being stirred up from the deep ocean into shallower waters by the tsunami, creating an ideal environment for bacteria that thrive on iron. Additionally, the meteorite likely introduced phosphorus to Earth’s ecosystem, a critical element for life. Increased erosion on land further contributed to the influx of these elements into the seas.

The combined availability of iron and phosphorus is thought to have fuelled the growth of single-celled organisms, which played a key role in the evolution of early life. “The tsunami would have ripped up the sea floor, mixing elements in ways that hadn’t occurred before,” Drabon explained, painting a vivid picture of the dramatic changes triggered by the impact. Evidence of the S2 strike is still visible today in the Barberton Greenstone Belt in South Africa, where scientists have uncovered traces of the massive event.

The Earth, at the time of S2’s impact, was roughly 1.5 billion years old. The study provides crucial insights into how such cataclysmic events, rather than just hindering life, may have shaped and advanced the development of early organisms, offering new perspectives on the conditions that led to the rise of life on our planet.